<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    
</body>
<script>
    //数组长度  数组名  .length
    var arr = ['a','b','c','d','e','f','g'];
    for (var i = 0;i<7;i++){
        console.log(arr[i]);
    }
    console.log(arr.length);

    // for (var i = 0; i < arr.length; i++){
    //     console.log(arr[i]);
    // }

    //1.数组的长度是元素个数   不要跟索引号混淆
    //2.arr.length 动态监测数组元素的个数
</script>
</html>